CN1907636A - Oxidation resistance tin-based no-lead solder capable of proceeding welding without welding flux in air - Google Patents

Abstract

The invention discloses an oxidation-resistant tin-based lead-free solder capable of flux-free soldering in air, which consists of 0.1-6 parts by weight of silver Ag, 0.5-6 parts by weight of titanium Ti, and 0.1-2.5 parts by weight of yttrium Y And the balance of tin Sn composition. The solder of the invention can directly weld materials of the same type and different types without using any flux in the air at a welding temperature of 240°C to 260°C. The joint shear strength of the oxidation-resistant tin-based lead-free solder is 30-50 MPa.

Description

An oxidation-resistant tin-based lead-free solder capable of flux-free soldering in air

technical field

The invention belongs to the field of welding and relates to a brazing material. Specifically, it refers to a combination of similar and dissimilar materials that can directly weld metal and metal, metal and non-metal, non-metal and non-metal in the air without using any flux, especially suitable for welding between ceramics and ceramics, ceramics and metals Oxidation-resistant tin-based lead-free solder.

Background technique

Since lead and its compounds in tin-lead solder are highly toxic substances, which seriously endanger the living environment and safety of human beings, countries all over the world have banned the use of lead-containing solder. Therefore, a series of lead-free solders have been developed at home and abroad, such as Sn-Zn, Sn-Ag, Sn-Ag-Cu, etc., but these solders can only solder metals, and flux must be used. The flux may cause environmental pollution, and some fluxes also need to be cleaned after welding, and the cleaning process will also cause certain pollution to the environment.

To fundamentally solve the above problems, flux-free brazing technology is imperative. Abroad has done a lot of research on this, such as Japan's Hitachi Manufacturing Co., Ltd. removed the oxide film by sputtering Ar atoms, and realized flux-free brazing in an atmosphere protection environment; Japan's Mitsubishi Electric Corporation developed laser flux-free brazing in an oxygen-free atmosphere. Brazing method; Fujitsu Corporation of Japan has developed a VPS flux-free soldering method by evaporating In on the substrate and chip electrodes, and then soldering with reflow soldering method; Solder, using high-temperature and high-pressure nitrogen heating to realize flux-free brazing, etc. The above-mentioned method has the following disadvantages: 1. It needs to be welded under protective atmosphere conditions; 2. The above-mentioned method cannot directly weld non-metals such as ceramics.

Although the solder disclosed in the patent document WO9703789 (Alloy, in particular a solder alloy, method for joining workpieces by soldering using the solder alloy and use of the alloy for soldering) can solder most non-metallic materials such as metals and ceramics without using flux Combination, but the components disclosed in this patent document contain lead elements, and it is necessary to take measures to protect the gas or remove surface oxides during the welding process.

At present, there are many connections between ceramics and ceramics and between ceramics and metals in the production of electronic products. Due to the huge difference in the structure and properties of ceramics and metals, ceramics and metals are connected at relatively low temperatures. Generally, the surface of ceramics is metallized and then brazed. Welding process method. Therefore, in order to overcome the problems existing in the above-mentioned soldering technology, the present invention provides a new type of lead-free solder that can directly weld metal to metal, metal to nonmetal, nonmetal to nonmetal, etc. in the air without using any flux. Solder in combination with dissimilar materials.

Contents of the invention

The object of the present invention is to provide a kind of oxidation-resistant tin-based lead-free solder that can be soldered without flux in the air. The oxidation-resistant tin-based lead-free solder is added by adding antioxidant element yttrium Y in the Sn-Ag-Ti system, Effectively realize the welding of metal and metal, metal and non-metal, non-metal and non-metal and other similar and dissimilar material combinations, and the solder of the present invention can be directly welded in air, without flux, and at a welding temperature of 240-260 ° C. Do the welding.

The invention is an anti-oxidation tin-based lead-free solder capable of flux-free soldering in air, which consists of 0.1-6 parts by weight of silver Ag, 0.5-6 parts by weight of titanium Ti, 0.1-2.5 parts by weight of yttrium Y and The balance is composed of tin and Sn. The oxidation-resistant tin-based lead-free solder is prepared by vacuum smelting, and the prepared Sn-0.1-6wt% Ag-0.5-6wt% Ti-0.1-2.5wt% Y solder can be used in the air without any flux 1. Under the condition of welding temperature 240-260 ℃, directly weld the welding objects of the same and dissimilar material combinations such as metal and metal, metal and non-metal, non-metal and non-metal.

The anti-oxidation tin-based lead-free solder capable of flux-free soldering in air has a joint shear strength of 30-50 MPa.

The advantages of the anti-oxidation tin-based lead-free solder of the present invention are: 1. The solder does not contain lead and does not use any flux, which completely guarantees the green performance of the solder; 2. It can be directly soldered in the air and has certain oxidation resistance , avoiding the complexity of the process and equipment brought about by the use of gas or vacuum protection; 3. It can directly braze the combination of similar and dissimilar materials (including metals and non-metals), especially more suitable for ceramics and ceramics in electronic products. Combination with metals, and can also weld other difficult-to-solder metals or non-metallic materials, such as titanium, graphite, silicon and composite materials; The temperature is basically the same, and the workpiece is lightly oxidized, which improves the connection quality and performance.

Detailed ways

The present invention will be further described in detail below in conjunction with examples.

The invention is an anti-oxidation tin-based lead-free solder capable of flux-free soldering in air, which consists of 0.1-6 parts by weight of silver Ag, 0.5-6 parts by weight of titanium Ti, 0.1-2.5 parts by weight of yttrium Y and The balance is composed of tin and Sn.

The oxidation-resistant tin-based lead-free solder of the present invention is prepared by vacuum smelting,

Step 1, putting 0.1-6 parts by weight of silver Ag, 0.5-6 parts by weight of titanium Ti, 0.1-2.5 parts by weight of yttrium Y and the rest of tin Sn materials into a non-consumable vacuum electric arc furnace;

Step 2: Vacuumize to 1×10 ^-1 ~ 1×10 ^-2 Pa, and then fill with high-purity argon;

Step 3, adjusting the melting temperature to 1400°C to 1600°C and the melting time to 5 to 30 minutes to make ingots;

Step 4, taking out the Sn-0.1-6wt%Ag-0.5-6wt%Ti-0.1-2.5wt%Y solder ingot after being cooled in the furnace.

In the third preparation step of vacuum smelting, Sn, Ag, Ti, and Y elements can be smelted in the furnace for about one to five times according to the amount of solder, so that the solder can be smelted evenly.

In order to compare the oxidation resistance of the solder after adding the anti-oxidation element Y, the inventors compared the Sn-4wt%Ag-4wt%Ti solder and the Sn-4wt%Ag-4wt%Ti-0.5wt%Y solder at a soldering temperature of 250°C Under the conditions, the thickness of the oxide film on the surface of the solder after heating (analyzed by Auger electron spectroscopy), under the same process specification conditions, the thickness of the oxide film on the surface of the Sn-4wt%Ag-4wt%Ti solder has reached 59nm, However, the thickness of the oxide layer on the surface of the Sn-4wt%Ag-4wt%Ti-0.5wt%Y solder is only 12nm. This proves that the Sn-4wt%Ag-4wt%Ti-0.5wt%Y solder disclosed in the present invention has good oxidation resistance. The addition of the anti-oxidation element Y solves the problems that the Sn-4wt%Ag-4wt%Ti solder must be protected by gas due to surface oxidation during the soldering process, which brings about the increase of equipment and the complexity of the process. The Sn-4wt%Ag-4wt%Ti-0.5wt%Y solder of the present invention simplifies the welding process (no protective atmosphere, no flux, direct welding) and reduces the welding cost (no protective gas equipment, simplifies the welding equipment structure).

The Sn-0.1～6wt%Ag-0.5～6wt%Ti-0.1～2.5wt%Y solder of the present invention can realize direct welding between combinations of similar and dissimilar materials (including metals and nonmetals) without using any flux in the air . The welding objects can be metal materials such as aluminum and aluminum alloys, copper and copper alloys, steel, stainless steel, titanium alloys, cast iron, hard alloys, nickel-based alloys; diamonds, graphite, intermetallic compounds, metal matrix composites and Non-metal matrix composite materials; it can also be ceramic materials such as alumina, zirconia, silicon nitride, aluminum nitride, titanium nitride, silicon carbide, chromium carbide, tungsten carbide, and molybdenum carbide. For the welding of different welding objects, please refer to the following disclosed embodiments. The embodiments are only used to illustrate the feasibility of the solder of the present invention, and shall not be used to limit the practical use of the solder of the present invention.

The Sn-0.1～6wt%Ag-0.5～6wt%Ti-0.1～2.5wt%Y solder of the present invention is especially suitable for direct welding between ceramic materials and ceramic materials in electronic products, or between ceramic materials and metal materials Direct welding, welding process without any flux.

Embodiment 1: making Sn-4wt%Ag-2wt%Ti-0.5wt%Y solder

Weigh Sn, Ag, Ti and Y materials by weight, put them into a non-consumable vacuum electric arc furnace, evacuate to 1×10 ^-2 , and fill with high-purity argon; adjust the melting temperature to 1500°C, and the melting time to 10 minutes; The material in the furnace is smelted evenly and cast into an ingot, which is taken out after cooling with the furnace; then, the Sn-4wt%Ag-2wt%Ti-0.5wt%Y solder ingot is rolled into a 25mm×5mm×0.5 mm flakes.

Use the above-mentioned Sn-4wt%Ag-2wt%Ti-0.5wt%Y solder for different welding objects, and heat the welding objects with a temperature-controlled resistance furnace. The shear strength of the welded joints is shown in the following table:

welding object Soldering temperature (℃) Joint shear strength (MPa) Alumina Ceramics/Alumina Ceramics   250°C±5°C 31MPa Zirconia Ceramics/Zirconium Oxide Ceramics   255°C±5°C 39MPa Aluminum Nitride Ceramics / Aluminum Nitride Ceramics   245°C±5°C 30MPa Silicon Nitride Ceramics/Silicon Nitride Ceramics   250°C±5°C 37MPa Alumina Ceramic/Copper   250°C±5°C 31MPa Alumina Ceramic/Aluminum   250°C±5°C 39MPa Alumina ceramic/stainless steel   250°C±5°C 30MPa Zirconia Ceramic/Aluminum   255°C±5°C 48MPa Zirconia Ceramic/Stainless Steel   255°C±5°C 39MPa Zirconia ceramic/copper   255°C±5°C 45MPa Silicon Nitride Ceramic/Stainless Steel   250°C±5°C 43MPa Silicon Nitride Ceramic/Aluminum   250°C±5°C 35MPa Silicon Nitride Ceramic/Copper   250°C±5°C 39MPa Aluminum Nitride Ceramic/Copper   245°C±5°C 30MPa aluminum/aluminum   245°C±5°C 47MPa aluminum/copper   245°C±5°C 48MPa aluminum/stainless steel   245°C±5°C 50MPa copper/copper   245°C±5°C 45MPa copper/stainless steel   245°C±5°C 42MPa stainless steel/stainless steel   245°C±5°C 47MPa

Test conditions: After welding the different welding objects in the above table with solder, use the MTS-880 universal material testing machine to test the shear strength of the welded joint of the above-mentioned Sn-4wt%Ag-2wt%Ti-0.5wt%Y solder.

Embodiment 2: making Sn-6wt%Ag-6wt%Ti-2.5wt%Y solder

Weigh Sn, Ag, Ti and Y materials by weight and put them into a non-consumable vacuum electric arc furnace, evacuate to 5×10 ^-2 , and fill with high-purity argon; adjust the melting temperature to 1500°C, and the melting time to 10 minutes; The inner material is smelted evenly and cast into an ingot, which is taken out after cooling with the furnace; then, the Sn-6wt%Ag-6wt%Ti-2.5wt%Y solder ingot is rolled into 25mm×5mm×0.5mm by cold rolling process of flakes.

Use Sn-6wt%Ag-6wt%Ti-2.5wt%Y solder for different welding objects, and heat the welding objects with a temperature-controlled resistance furnace. The shear strength of the welded joints is shown in the following table: welding object Soldering temperature (℃) Joint shear strength (MPa) Alumina Ceramics/Alumina Ceramics 250℃±5℃ 31MPa Zirconia Ceramics/Zirconium Oxide Ceramics 255℃±5℃ 39MPa Aluminum Nitride Ceramics / Aluminum Nitride Ceramics 245℃±5℃ 30MPa Silicon Nitride Ceramics/Silicon Nitride Ceramics 250℃±5℃ 37MPa Alumina Ceramic/Copper 250℃±5℃ 31MPa Alumina Ceramic/Aluminum 250℃±5℃ 39MPa Alumina ceramic/stainless steel 250℃±5℃ 30MPa Zirconia Ceramic/Aluminum 255℃±5℃ 48MPa Zirconia Ceramic/Stainless Steel 255℃±5℃ 39MPa Zirconia ceramic/copper 255℃±5℃ 45MPa Silicon Nitride Ceramic/Stainless Steel 250℃±5℃ 43 MPa Silicon Nitride Ceramic/Aluminum 250℃±5℃ 35MPa Silicon Nitride Ceramic/Copper 250℃±5℃ 39MPa Aluminum Nitride Ceramic/Copper 245℃±5℃ 30MPa aluminum/aluminum 245℃±5℃ 47Mpa aluminum/copper 245℃±5℃ 48MPa aluminum/stainless steel 245℃±5℃ 50MPa copper/copper 245℃±5℃ 45MPa copper/stainless steel 245℃±5℃ 42MPa stainless steel/stainless steel 245℃±5℃ 47MPa

Test conditions: After welding the different welding objects in the above table with solder, use the MTS-880 universal material testing machine to test the shear strength of the welded joint of the above-mentioned Sn-6wt%Ag-6wt%Ti-2.5wt%Y solder.

Example 3: Disclosure of Joint Shear Strength of Different Solder Compositions

For the Sn-0.1～6wt%Ag-0.5～6wt%Ti-0.1～2.5wt%Y solder disclosed in the present invention, see the following table for the joint shear strength of the same welding object using different component solders: welding object Solder (parts by weight) Soldering temperature (℃) Joint shear strength (Mpa) sn Ag Ti Y Alumina Ceramic/Copper margin 0.1 0.5 0.1 250℃±5℃ 32MPa 0.5 1 0.5 39MPa 3 3 0.4 37MPa 3 3 1 35MPa 5 3 2 37MPa 2 2 0.8 39MPa 4 2 0.5 37MPa 4 2 0.2 35MPa 4 4 1.5 40MPa 4 3 1 35MPa 6 6 2.5 37MPa

Melting equipment: non-consumable vacuum electric arc furnace

Melting conditions: vacuum to 1×10 ^-2 , filled with high-purity argon;

The melting temperature is 1500°C, and the melting time is 10 minutes to cast ingots;

Welding conditions: welding temperature 250°C±5°C, and use a conventional desktop resistance furnace to heat the welding object;

Test conditions: MTS-880 universal material testing machine was used to test the shear strength of the soldered joint of the above-mentioned Sn-6wt%Ag-6wt%Ti-2.5wt%Y solder.

It can be seen from the above table that the content of the anti-oxidation element yttrium Y is closely related to the content change of the active element titanium Ti. In the actual soldering process, the oxide layer on the surface of the solder is mainly composed of tin and titanium oxides, and the addition of anti-oxidation element yttrium Y mainly inhibits the formation of titanium oxide.

Claims (10)

1, a kind of oxidation resistance tin-based no-lead scolder that can in air, carry out the fluxless welding, comprise tin Sn, silver-colored Ag, titanium Ti element, it is characterized in that: also comprise the yttrium Y element, described oxidation resistance tin-based no-lead scolder is made up of silver-colored Ag, the titanium Ti of 0.5～6 weight portion, the yttrium Y of 0.1～2.5 weight portion and the tin Sn of surplus of 0.1～6 weight portion.

2, the oxidation resistance tin-based no-lead scolder that can carry out fluxless welding in air according to claim 1 is characterized in that: described oxidation resistance tin-based no-lead scolder is directly the welding object between metal and metal, metal and nonmetal, nonmetal and the nonmetallic materials to be welded in air, under the condition of 240～260 ℃ of fluxless, welding temperature.

3, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 2 is characterized in that: described Metal Material Welding is to liking aluminium and aluminium alloy, copper and copper alloy, steel, stainless steel, titanium alloy, cast iron, carbide alloy and nickel-base alloy; Described nonmetallic materials welding object is diamond, graphite, intermetallic compound, metal-base composites and non-metal-matrix composite, and the ceramic material of aluminium oxide, zirconia, silicon nitride, aluminium nitride, titanium nitride, carborundum, chromium carbide, tungsten carbide and molybdenum carbide.

4, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 1, it is characterized in that: described oxidation resistance tin-based no-lead scolder is Sn-4wt%Ag-2wt%Ti-0.5wt%Y.

5, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 1, it is characterized in that: described oxidation resistance tin-based no-lead scolder is Sn-5wt%Ag-3wt%Ti-2wt%Y.

6, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 1, it is characterized in that: described oxidation resistance tin-based no-lead scolder is Sn-4wt%Ag-3wt%Ti-1wt%Y.

7, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 1, it is characterized in that: described oxidation resistance tin-based no-lead scolder is Sn-4wt%Ag-2wt%Ti-0.5wt%Y.

8, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 1, it is characterized in that: described oxidation resistance tin-based no-lead scolder is Sn-4wt%Ag-2wt%Ti-0.2wt%Y.

9, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 1, it is characterized in that: described oxidation resistance tin-based no-lead scolder is Sn-3wt%Ag-3wt%Ti-0.4wt%Y.

10, the oxidation resistance tin-based no-lead scolder that can carry out the fluxless welding in air according to claim 1 is characterized in that: the shearing strength of joint of described oxidation resistance tin-based no-lead scolder welding is 30～50MPa.